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linux-stable/drivers/vfio/platform
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Alex Williamson 62d4e43a56 vfio/platform: Create persistent IRQ handlers 
commit 675daf435e upstream.

The vfio-platform SET_IRQS ioctl currently allows loopback triggering of
an interrupt before a signaling eventfd has been configured by the user,
which thereby allows a NULL pointer dereference.

Rather than register the IRQ relative to a valid trigger, register all
IRQs in a disabled state in the device open path.  This allows mask
operations on the IRQ to nest within the overall enable state governed
by a valid eventfd signal.  This decouples @masked, protected by the
@locked spinlock from @trigger, protected via the @igate mutex.

In doing so, it's guaranteed that changes to @trigger cannot race the
IRQ handlers because the IRQ handler is synchronously disabled before
modifying the trigger, and loopback triggering of the IRQ via ioctl is
safe due to serialization with trigger changes via igate.

For compatibility, request_irq() failures are maintained to be local to
the SET_IRQS ioctl rather than a fatal error in the open device path.
This allows, for example, a userspace driver with polling mode support
to continue to work regardless of moving the request_irq() call site.
This necessarily blocks all SET_IRQS access to the failed index.

Cc: Eric Auger <eric.auger@redhat.com>
Cc:  <stable@vger.kernel.org>
Fixes: 57f972e2b3 ("vfio/platform: trigger an interrupt via eventfd")
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20240308230557.805580-7-alex.williamson@redhat.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2024-04-03 15:28:49 +02:00
..
reset vfio/platform: Cleanup Kconfig 2023-06-16 12:23:50 -06:00
Kconfig vfio/platform: Cleanup Kconfig 2023-06-16 12:23:50 -06:00
Makefile vfio/platform: Cleanup Kconfig 2023-06-16 12:23:50 -06:00
vfio_amba.c vfio-iommufd: Add detach_ioas support for physical VFIO devices 2023-07-25 10:19:12 -06:00
vfio_platform.c vfio-iommufd: Add detach_ioas support for physical VFIO devices 2023-07-25 10:19:12 -06:00
vfio_platform_common.c vfio: platform: ignore missing reset if disabled at module init 2023-02-01 12:25:41 -07:00
vfio_platform_irq.c vfio/platform: Create persistent IRQ handlers 2024-04-03 15:28:49 +02:00
vfio_platform_private.h vfio/amba: Use the new device life cycle helpers 2022-09-21 14:15:11 -06:00